Odpowiedź:
f(x) = x² + 3x + k ; f(-2) = 1
1 = (- 2)² + 3 * (- 2) + k
1 = 4 - 6 + k
1 = -2 +k
k = 1 + 2 =3
2
4cos²α - 3/4 = 1
4cos²α = 1 + 3/4 = 1 3/4 = 7/4
cos²α= 7/4 : 4 = 7/4 * 1/4 = 7/16
1 - sin²α = 7/16
sin²α = 1 - 7/16 = 9/16
sinα = √(9/16) = 3/4
3.
(cos109° + sin19°)² = [cos(180° - 71°) + sin(90° - 19°)]² = (- cos71° + cos71°)² =
= 0² = 0
